Primary length on a header.

[vega]

So I found out that the headers (from bbk made for a ford modified to be used on a sbc d port) yes, are indeed equal. Albeit they are 17.5 inches in length, the primaries that is. According to the length equation from "headers by ed" {(CID * 1900)/(rpm_max * tube_od2)} the recommended length is 34.2 inches.

 

This being said, what is going to change in using 17.5 inch primaries vs 34.2 inch primaries aside from a higher exhaust note?

[Leon]

So I found out that the headers (from bbk made for a ford modified to be used on a sbc d port) yes, are indeed equal. Albeit they are 17.5 inches in length, the primaries that is. According to the length equation from "headers by ed" {(CID * 1900)/(rpm_max * tube_od2)} the recommended length is 34.2 inches.

 

This being said, what is going to change in using 17.5 inch primaries vs 34.2 inch primaries aside from a higher exhaust note?

This has been discussed in excruciating detail. Look at the exhaust sticky, and I'm sure it's been mentioned elsewhere on the forum. In a nutshell, shorter primaries will shift your powerband to higher rpm because of resonance tuning.

[vega]

Thank you for the link, and the patience.

[grumpyvette]

http://forum.grumpysperformance.com/viewtopic.php?f=56&t=961

 

http://forum.grumpysperformance.com/viewtopic.php?f=56&t=1303

 

http://forum.grumpysperformance.com/viewtopic.php?f=56&t=495

 

http://forum.grumpysperformance.com/viewtopic.php?f=56&t=185

 

http://forum.grumpysperformance.com/viewtopic.php?f=56&t=1503

 

if your interested in more info